Marine speedometer and anemometer with digital readout

ABSTRACT

A marine speedometer and anemometer utilizing a common computer circuit and having an electro-luminescent display. A selector switch connects a pulse source and at the same time selects the proper computer circuits to produce a direct digital readout of ship or wind speed in knots or miles per hour. The pulses sources are a propeller device installed beneath the boat in the water and a cup or vane type anemometer rotor device mounted in the open where it can be driven by the wind. The digital display is mounted in a deep enclosure along with the computer circuitry and is fitted with a non-reflecting filter and window for protection against water and weather and to insure good legibility in bright or dark lighting.

' PATENTEDJUU 8 m2 PRQPELLER ASSEMBLY I SH\P o-99- SHIP 0-9.9

OFF-J 8 D\c- \TAL. READOUT ASSEMBLY SHEET 1 OF 2 COMPUTER C I RCU ITS iANEMOMETER ASSEMBLY QZNVENTOR MARINE SPEEDOMETER AND ANEMOMETER WITHDIGITAL READOUT BACKGROUND OF THE INVENTION In the sailing and boatingart it is very important to have an accurate knowledge of the boat speedthrough the water, and of the wind speed past the boat. To date, devicesfor providing this information have generally displayed instantaneousdata on meter or dial type instruments. This data is often spurious,hard to read and inaccurate at low speeds. The devices or instrumentsare also sensitive to eddy currents and gusts with the result thatreadings are unsteady and difficult to interpret.

SUMMARY OF THE INVENTION Accordingly, it is an object of thisinventionto provide, an easy-to-read digital format, boat speed and wind speedaveraged over afinite period of time, thereby eliminating transient windand water effects. Also, by displaying wind or water speed as determinedby pulse data obtained over a period of time, a very high order ofaccuracy can be realized, making possible readings in tenths of knots ormiles per hour. A common computer and'display is used for economy.However, the use of additional components will permit asimultaneousdisplayof wind and boat speed and also duplicate displays atother locations on the boat.

The foregoing features and advantages will become more apparent in lightof the following detailed description and drawings of the invention.

\ BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the majorcomponents and features of the invention along with details of theinterconnecting cabling.

FIG. 2. illustrates, in schematic form, the basic computer circuitrywhich is used to produce the proper digital readout of boat or windspeed.

' rotor assembly 3 which rotates on its shaft 3A when the wind blowsagainst the cups 313 causes the reed switch 3C to close each time therotor magnets 3D revolve past. The switches are connected to thecomputer 4 by means of the cables 5 and 6. Theselector switch 7, mountedon the front of the digital readout assembly 8, is used to select thewind or ship speed range, switch on power to the computer circuit fromthe power source 9, and to connect one of the cable inputs 5 or 6 to thecomputing circuit 4. The computing circuitry 4 will, depending on therange selected by switch 7, convert the number of closings of theswitches 1C or SC to a digital display of speed on theelectro-luminescent tubes 10.

The computer circuitry 4 which is enclosed in the digital displayassembly 8 works in the following manner. The computer circuitryreshapes the switch signals from switches 1C or 3C to form sharpwell-defined pulses. These pulses are then fed to a counter circuitwhich counts the total number of pulses generated in a period of timeestablished by the range selected by the selector switch 7. The computergenerates two pulses which signal the end of the count period andtransfers into a storage register or memory bank the total number ofpulses generated in the time period and resets the counter back to zeroin preparation for the next count period. The count data in the storageregister is then displayed by means of a decoder driver stage on asegmented type electroluminescent tube 10. The display is held constantfor the entire new count period. At the end of this new count period thepulse count data in the storage register is replaced by the new countdata and the counter reset to zero as before. The newly entered countdata is now displayed by the decoder driver on the electro-luminescenttubes l0.

Because the count data is accumulated over a period of time.

the display data represents a true average reading of speed for eachsample period. The display is in the form of a sharp welldefined numeralformed by the segments of the electro-luminescent tubes 10 and iscompletely steady and unblinking, making possible easy error-freereading. To further enhance the readability of the display tubes anon-reflecting Polaroid film 11 is placed over the tubes to eliminatereflection or glare which might be produced on the glass tube envelopein bright sunlight. Protection of the display tubes and electroniccircuitry is also insured by the positioning of a transparent window 12over the opening and sealed with sealant 13 in the digital displayenclosure 8. This window 12 is sloped at 45 degrees to prevent glare orreflections from its surface from interfering with ease of reading.

High reading accuracy is possible with the digital readout because thetime base or count period can be changed by means of the selector switch7 to obtain larger or smaller pulse samples as desired. In the preferredembodiment shown in FIG. 1, the use of two display tubes is indicatedfor reasons of economy. As shown, the display is able to read out speedsof from 0 to 9.9 or 0 to 99 knots or miles per hour. In the first 0 to9.9 range the selector switch is also used to switch on the decimalpoint 10A, thereby giving the ability to read in tenths of a knot ormoles per hour. If the computer circuit were al tered or adjusted toallow a count period equal to ten times that normally used in the 0 to9.9 range, the device would then display 0 to .99 knots or miles perhour with an accuracy of a hundreth of a knot or mile per hour.

High accuracy is also possible because individual components such as thepropeller assembly 1 and the anemometer assembly 3 can be accuratelymatched or calibrated after installation with the digital readoutassembly 8 by means of adjustment potentiometers to allow for smallvariation in manufacture.

It may also be understood that other switching devices other than thereed switches 1C and 3C may be used to provide suitable input for thecomputer circuitry 4. Examples of these alternates are Hall effectdevices, photovoltaic cells and lamps, variable reluctance devices,magneto type devices and mechanical switches. Similarly, other types ofdisplay tubes such as incandescent segmented lamps, neon or nixienumerical display lamps, fiber optic or light conductive plastic orglass segmented displays using individual incandescent bulbs forillumination could also be used.

Details of the computer circuitry 4 in FIG. 1 are shown in the schematicdiagram in FIG. 2. In this diagram the several inputs and power supplyconnections are made by means of the selector switch 7 in FIG. 1. Theselector switch consists of two sections or decks, each of which hasthree poles with four positions including an OFF position. One of thedecks is arranged to supply power to the circuit at 36 Volts DC, l8Volts DC and 1.6 Volts DC for all three ON pole positions. Thesevoltages provide the potentials necessary to illuminate the segments ofthe electro-luminescent tubes 10, provide power to the timing, pulseforming, and computer stages, and provide filament power to theelectro-luminescent tubes 10.

One pole of the second selector switch 7 deck applies positive groundvoltage to a selected range input. A second pole provides the means ofconnecting the cable 6 from the propeller assembly 1 to the pulse inputterminal for switch positions 1 and 2. This second pole also connectscable 5 from the anemometer rotor assembly 3 to the pulse input terminalin position 3. The third pole of the second deck is used to apply 36Volts DC to the dot input when the selector switch 7 is rotated to thefirst position, thereby providing the decimal point 10A in the readouttube 10 for the 0 to 9.9 range.

In an alternate design, a DC to DC converter is used to provide theseveral voltage inputs. In this case the selector switch 7 connects thepower source 9 such as a 12 volt battery to the converter. The selectorswitch 7 continues to perform all other switching functions described.

The digital display tubes are operated by means of the two monolithicintegrated circuits l4 and which drive the tubes 10 in the units andtens position, respectively. The integrated circuits l4 and 15 aredesigned to operate with seven segment numerical indicator tubes andcontain a one decade up-down BCD counter, a storage register, a BCD toseven segment decoding matrix, and driver stage. The integrated circuitsl4 and 15 which are commercially available from several sources isdesigned to perform the function of counting pulses generated by theswitches 1C or 3C over a given period of time and upon a pulse commandto enter the count total into a storage register and to display thecount number on the electro-luminescent tubes 10. Another pulse commandwill reset the counter'back to zero and allow a new count to be madeover the next time period while the previous count is being displayed.Since the propeller 1A or rotor assembly 3 turn or rotate indirectproportion to water or wind speed, it is possible by proper selection oradjustment of the time period over whichthe count is taken to obtain acount total'which is the exact equivalent of ship or wind speed in knotsor miles per hour. 1

Closing of the switches 1C or 3C-in FIG. lconnects the negativevoltageItothe pulse'input terminal in FIG. 2. This negative voltage iscoupled by meansof the filter formed by resistor 16 andcapacitor l7 andthe differentiating network formed. by capacitor 18 and resistor 19through resistor 20 to the base of transistor 21. Transistor 21conducts, producing a sharp pulse across resistor 22 and capacitor 23which is fed to the integrated circuit 14 counter input at pin 1 l. Thepulses so entered are accumulated by the counter until a count of ten isreached. At this count the'integrated circuit 14 produces a pulse on pin2 which is coupled to pin 11 input of the integrated circuit 15. Thecount will continue in this manner until a command is given to enter thecount into the storage register where it is held for decoding anddisplaying.

The time period is established by means of the unijunction 27 and itsassociated RC circuitry. The selector switch 7 applies positive voltageto a selected range input allowing a charge to build up on the capacitor26 through resistor 24 and potentiometer 25. The unijunction 27 remainsnon-conductive until the capacitor 26 charge reaches the triggeringlevel of the unijunction 27. At this time the unijunction 27 conducts,discharging the capacitor 26 through itself and the resistor 29 andgenerating a negative timing pulse across the resistor 28.

This timing pulse is coupled by the capacitor 30 and resistor 31 to thebase of the transistor 33. Both transistor 27 and 33 are normally biasedoff by the resistors 37 and 32 which are connected to the positiveground. When the negative timing pulse is applied to the base of thetransistor 33 it conducts, causing the voltage drop across the resistor34 to increase. This voltage pulse is carried to pin 7 of the integratedcircuits l4 and 15 to command the count total accumulated to betransferred to the storage register. When the pulse fed to thetransistor 33 base ends, the transistor 33 ceases to conduct and thepositive voltage pulse developed across the resistor 34 returns to amore negative value. This negative swing of the collector on transistor33 is coupled by the capacitor 39 and resistor '38 to the base of thetransistor 36 which in turn begins to conduct. A positive pulse isdeveloped across the resistor 35 and fed to pin 4 of the integratedcircuits 14 and 15 where it resets the counter circuit back to zero inpreparation for the next count. After a short period determined by thevalues of the capacitor 39 and resistors 37 and 38, the transistor 36will again turn off, restoring the circuit to its original state.

As the next count proceeds, the data entered in the storage register isdecoded and displayed by the integrated circuits l4 and 15. The circuitsfunction the same on all ranges. The only variation is in the timingperiod which is chosen with the selector switch 7.

The potentiometers 25 are used to make fine or vernier adjustments inthe tinting periods as required to compensate for installation orpropeller or rotor component variations.

lie the principles of the above invention have been described inconnection with specific embodiments and particular modificationsthereof, it is to be clearly understood that this description is made byway of example and not as a limitation of the scope of the invention; 1claim 1. A digital readout boat speedometer-anemometer system, providingmeans for counting and displaying in velocity units the electricalpulses received from an anemometer device or a water speed device over apredetermined period, including; means for resetting the electricalpulse counting portion of the system to zero prior to starting a newcounting period; means for signalling the count device to start countingafter it has been reset; means for providing and selecting controlsignals from a plurality of predetermined count time interval circuitsto provide a stop count signal after the selected time interval haselapsed; means for providing a signal to a storing device to store anddisplay digitally the sum of counts made; means for steadily holding anddisplaying digitally the period count just made while the consecutiveperiod count is being made;

means for selecting and providing electrical pulses to the counter at arate proportional to the velocity of either an anemometer or a waterspeed device; means for interlocking the said proper predetermined counttime interval with the said selected velocity source such that the sumof the period count when displayed reads directly in standard velocityunits whereby said system functions to select a velocity source, countits pulses over a selected time period, then store and convert thiscount to a digital display while a consecutive count is being made, thusa velocity reading is continuously displayed.

2. A system according to claim 1 which includes circuitry and trimmingdevices such that the predetermined time periods can be adjusted so thatinstallation variations in the velocity indicators either anemometers orwater speed devices can be compensated for and true velocity readingsdisplayed, this same trimming device permits adjustment to display knotsor miles per hour.

3. A system according to claim 1 in which the anemometer rotor for windspeed indication and submerged propeller for water speed indicationprovide pulses at a rate proportional to velocity, said rate beingcontrolled by anemometer arm length and propeller angle and number ofpulses generated by each revolution of same, said pulse rate chosen bydesign to provide updating of the display over intervals-of 0.2 to 2.5seconds to provide a pleasing and easily readable display withoutsacrifice of dynamic response and means to provide longer or shorterperiods.

4. A system according to claim 1 in which since the air and water drivendevices provide pulses per unit of velocity and the display is in unitscontrolled directly by the time period control, and with a plurality ofpredetermined time periods different scale ranges are provided to beselected by the operator as desired, permitting the operator to selectvarious wind or ship speed ranges as desired for display.

5. A system according to claim 1 including an electroluminescent displaywith shades and polarized filter to permit viewing of the digitaldisplay of speed in daylight or at night without supplementaryillumination.

6. A system according to claim 1 which includes a conventionalconversion circuit such that a single source of low voltage DC asavailable in small boats is also used to supply high voltages whererequired for proper operation, said circuit is designed for minimumconsumption of electric power.

7. A system according to claim 1 which by sealing all cable and switchentries and enclosing the display with a transparent cover is completelysealed for use in a marine environment.

1. A digital readout boat speedometer-anemometer system, providing meansfor counting and displaying in velocity units the electrical pulsesreceived from an anemometer device or a water speed device over apredetermined period, including; means for resetting the electricalpulse counting portion of the system to zero prior to starting a newcounting period; means for signalling the count device to start countingafter it has been reset; means for providing and selecting controlsignals from a plurality of predetermined count time interval circuitsto provide a stop count signal after the selected time interval haselapsed; means for providing a signal to a storing device to store anddisplay digitally the sum of counts made; means for steadily holding anddisplaying digitally the period count just made while the consecutiveperiod count is being made; means for selecting and providing electricalpulses to the counter at a rate proportional to the velocity of eitheran anemometer or a water speed device; means for interlocking the saidproper predetermined count time interval with the said selected velocitysource such that the sum of the period count when displayed readsdirectly in standard velocity units whereby said system functions toselect a velocity source, count its pulses over a selected time period,then store and convert this count to a digital display while aconsecutive count is being made, thus a velocity reading is continuouslydisplayed.
 2. A system according to claim 1 which includes circuitry andtrimming devices such that the predetermined time periods can beadjusted so that installation variations in the velocity indicatorseither anemometers or water speed devices can be compensated for andtrue velocity readings displayed, this same trimming device permitsadjustment to display knots or miles per hour.
 3. A system according toclaim 1 in which the anemometer rotor for wind speed indication andsubmerged propeller for water speed indication provide pulses at a rateproportional to velocity, said rate being controlled by anemometer armlength and propeller angle and number of pulses generated by eachrevolution of same, said pulse rate chosen by design to provide updatingof the display over intervals of 0.2 to 2.5 seconds to provide apleasing and easily readable display without sacrifice of dynamicresponse and means to provide longer or shorter periods.
 4. A systemaccording to claim 1 in which since the air and water driven devicesprovide pulses per unit of velocity and the display is in unitscontrolled directly by the time period control, and with a plurality ofpredetermined time periods different scale ranges are provided to beselected by the operator as desired, permitting the operator to selectvarious wind or ship speed ranges as desired for display.
 5. A systemaccording to claim 1 including an electroluminescent display with shadesand polarized filter to permit viewing of the digital display of speedin daylight or at night without supplementary illumination.
 6. A systemaccording to claim 1 which includes a conventional conversion circuitsuch that a single source of low voltage DC as available in small boatsis also used to supply high voltages where required for properoperation, said circuit is designed for minimum consumption of electricpower.
 7. A system according to claim 1 which by sealing all cable andswitch entries and enclosing the display with a transparent cover iscompletely sealed for use in a marine environment.